Association between sagittal alignment and loads at the adjacent segment in the fused spine: a combined clinical and musculoskeletal modeling study of 205 patients with adult spinal deformity.

PURPOSE: Sagittal malalignment is a risk factor for mechanical complications after surgery for adult spinal deformity (ASD). Spinal loads, modulated by sagittal alignment, may explain this relationship. The aims of this study were to investigate the relationships between: (1) postoperative changes in loads at the proximal segment and realignment, and (2) absolute postoperative loads and postoperative alignment measures. METHODS: A previously validated musculoskeletal model of the whole spine was applied to study a clinical sample of 205 patients with ASD. Based on clinical and radiographic data, pre-and postoperative patient-specific alignments were simulated to predict loads at the proximal segment adjacent to the spinal fusion. RESULTS: Weak-to-moderate associations were found between pre-to-postop changes in lumbar lordosis, LL (r = - 0.23, r = - 0.43; p < 0.001), global tilt, GT (r = 0.26, r = 0.38; p < 0.001) and the Global Alignment and Proportion score, GAP (r = 0.26, r = 0.37; p < 0.001), and changes in compressive and shear forces at the proximal segment. GAP score parameters, thoracic kyphosis measurements and the slope of upper instrumented vertebra were associated with changes in shear. In patients with T10-pelvis fusion, moderate-to-strong associations were found between postoperative sagittal alignment measures and compressive and shear loads, with GT showing the strongest correlations (r = 0.75, r = 0.73, p < 0.001). CONCLUSIONS: Spinal loads were estimated for patient-specific full spinal alignment profiles in a large cohort of patients with ASD pre-and postoperatively. Loads on the proximal segments were greater in association with sagittal malalignment and malorientation of proximal vertebra. Future work should explore whether they provide a causative mechanism explaining the associated risk of proximal junction complications.

Surgeons' risk perception in ASD surgery: The value of objective risk assessment on decision making and patient counselling.

BACKGROUND: Surgeons often rely on their intuition, experience and published data for surgical decision making and informed consent. Literature provides average values that do not allow for individualized assessments. Accurate validated machine learning (ML) risk calculators for adult spinal deformity (ASD) patients, based on 10 year multicentric prospective data, are currently available. The objective of this study is to assess surgeon ASD risk perception and compare it to validated risk calculator estimates. METHODS: Nine ASD complete (demographics, HRQL, radiology, surgical plan) preoperative cases were distributed online to 100 surgeons from 22 countries. Surgeons were asked to determine the risk of major complications and reoperations at 72 h, 90 d and 2 years postop, using a 0-100% risk scale. The same preoperative parameters circulated to surgeons were used to obtain ML risk calculator estimates. Concordance between surgeons' responses was analyzed using intraclass correlation coefficients (ICC) (poor < 0.5/excellent > 0.85). Distance between surgeons' and risk calculator predictions was assessed using the mean index of agreement (MIA) (poor < 0.5/excellent > 0.85). RESULTS: Thirty-nine surgeons (74.4% with > 10 years' experience), from 12 countries answered the survey. Surgeons' risk perception concordance was very low and heterogeneous. ICC ranged from 0.104 (reintervention risk at 72 h) to 0.316 (reintervention risk at 2 years). Distance between calculator and surgeon prediction was very large. MIA ranged from 0.122 to 0.416. Surgeons tended to overestimate the risk of major complications and reintervention in the first 72 h and underestimated the same risks at 2 years postop. CONCLUSIONS: This study shows that expert surgeon ASD risk perception is heterogeneous and highly discordant. Available validated ML ASD risk calculators can enable surgeons to provide more accurate and objective prognosis to adjust patient expectations, in real time, at the point of care.

Growth-Friendly Spine Surgery in Arthrogryposis Multiplex Congenita.

BACKGROUND: Arthrogryposis multiplex congenita (AMC) is a condition that describes neonates born with ≥2 distinct congenital contractures. Despite spinal deformity in 3% to 69% of patients, inadequate data exist on growth-friendly instrumentation (GFI) in AMC. Our study objectives were to describe current GFI trends in children with AMC and early-onset scoliosis (EOS) and to compare long-term outcomes with a matched idiopathic EOS (IEOS) cohort to determine whether spinal rigidity or extremity contractures influenced outcomes. METHODS: Children with AMC and spinal deformity of ≥30° who were treated with GFI for ≥24 months were identified from a multicenter EOS database (1993 to 2017). Propensity scoring matched 35 patients with AMC to 112 patients with IEOS with regard to age, sex, construct, and curve. Multivariable linear mixed modeling compared changes in spinal deformity and the 24-item Early Onset Scoliosis Questionnaire (EOSQ-24) across cohorts. Cohort complications and reoperations were analyzed using multivariable Poisson regression. RESULTS: Preoperatively, groups did not differ with regard to age (p = 0.87), sex (p = 0.96), construct (p = 0.62), rate of nonoperative treatment (p = 0.54), and major coronal curve magnitude (p = 0.96). After the index GFI, patients with AMC had reduced percentage of coronal correction (35% compared with 44%; p = 0.01), larger residual coronal curves (49° compared with 42°; p = 0.03), and comparable percentage of kyphosis correction (17% compared with 21%; p = 0.52). In GFI graduates (n = 81), final coronal curve magnitude (55° compared with 43°; p = 0.22) and final sagittal curve magnitude (47° compared with 47°; p = 0.45) were not significantly different at the latest follow-up after definitive surgery. The patients with AMC had reduced T1-S1 length (p < 0.001), comparable T1-S1 growth velocity (0.66 compared with 0.85 mm/month; p = 0.05), and poorer EOSQ-24 scores at the time of the latest follow-up (64 compared with 83 points; p < 0.001). After adjusting for ambulatory status and GFI duration, patients with AMC developed 51% more complications (incidence rate ratio, 1.51 [95% confidence interval (CI), 1.11 to 2.04]; p = 0.009) and 0.2 more complications/year (95% CI, 0.02 to 0.33 more; p = 0.03) compared with patients with IEOS. CONCLUSIONS: Patients with AMC and EOS experienced less initial deformity correction after the index surgical procedure, but final GFI curve magnitudes and total T1-S1 growth during active treatment were statistically and clinically comparable with IEOS. Nonambulatory patients with AMC with longer GFI treatment durations developed the most complications. Multidisciplinary perioperative management is necessary to optimize GFI and to improve quality of life in this complex population. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Early outcomes and complications of posterior vertebral column resection.

BACKGROUND CONTEXT: Hyperkyphosis confers a significant risk for neurologic deterioration as well as compromised cardiopulmonary function. Posterior vertebral column resection (PVCR) is a challenging but effective technique for spinal cord decompression and deformity correction that even under the setting of limited resources can be performed to reduce the technical difficulties, the operating time, and possibly the complications of the traditional two-staged vertebral column resection (VCR). PURPOSE: To report on the results of VCR performed through a single posterior approach (PVCR) in the treatment of severe rigid kyphosis in a series of patients treated and followed at a Scoliosis Research Society Global Outreach Program site in West Africa. STUDY DESIGN: Retrospective case series. PATIENT SAMPLE: Forty-five consecutive patients treated with PVCR for correction of severe rigid kyphosis. OUTCOME MEASURES: Clinical and radiographic outcomes and complications; Scoliosis Research Society outcome instrument (SRS-22). METHODS: From 2002 to 2009, 45 patients (20 male and 25 female) underwent PVCR for kyphosis from congenital deformity (nine) or secondary to tuberculosis of the spine (36). Preoperative demographics, preop and postop neurologic status, SRS-22 scores and complications were recorded; upright full spine X-rays were available in all patients. Mean age was 14 years (6-47 years); mean follow-up 27 months (2-79 months). Mean preoperative kyphosis measured 108°. The deformity apex was resected via a costotransverse (thoracic) or posterolateral (lumbar) approach; neurosurveillance with sensory (somatosensory-evoked potentials) and motor (motor-evoked potentials) potential was used in all cases. Posterior instrumentation was used in all patients, and anterior structural cage was used in 32 patients. RESULTS: Intraoperative monitoring changes occurred in 10 patients (22%), and one patient progressed to complete spinal cord injury. Average preoperative local kyphosis was 108° and corrected to 600 postoperatively. Postoperatively, no additional patient showed neurologic deterioration; of the 11 patients with preoperative gait disturbances, 4 improved to normal gait, 5 remained the same, and 2 showed deterioration of their walking ability to nonambulating level. Total SRS-22 scores improved from 3.18 to 3.54 (p=.01), primarily self-image domain. CONCLUSIONS: Posterior vertebral column resection was successfully undertaken for the management of thoracic and thoracolumbar hyperkyphosis, demonstrating improvements in overall kyphosis and clinical outcome. Neuromonitoring provided the required safety to perform these challenging complex spine deformity procedures.